Achoo! Every time you go near your best friend’s cat, your eyes water and you start sneezing up a storm. And every spring and fall, your dad gets a runny nose when he takes you for hikes in the woods

What’s going on? Well, you and your dad may have allergies.

Chain Reaction

An allergy (say: al-ur-jee) is your immune system’s reaction to certain plants, animals, foods, insect bites, or other things. Your immune system protects you from diseases by fighting germs like bacteria and viruses, but when you have allergies, it overreacts and tries to “fight” ordinary things like grass, pollen, or certain foods. This causes the sneezing, itching, and other reactions that you get with allergies.

The substances that cause allergies (grass, pollen, foods, pet byproducts, insects, etc.) are called allergens (say: al-ur-jenz). When your immune (say: ih-myoon) system reacts to one of these allergens and you have symptoms, you are allergic to it.

What Causes the Sneezing and Wheezing?

You can be allergic to many things. Common allergens include:

• dust mites (tiny insects that live in dust)

• a protein found in the dander (dry skin), saliva (spit), urine (pee), or other things from some animals

• grass, flower, and tree pollen (the fine dust from plants)

• mold and mildew (small living things that grow in damp places)

• foods, such as milk, wheat, soy, eggs, nuts, seafood, and legumes (say: leh-gyooms), which include peas, beans, and peanuts

• latex (stretchy stuff that some of the gloves doctors and dentists use are made of)

Symptoms

Some of these allergens cause sneezing, a runny nose, itchy eyes and ears, and a sore throat. Other items on the list, such as foods, may cause hives (a red, bumpy, itchy skin rash), a stuffy nose, stomach cramps, vomiting, or diarrhea.

Less often, allergens can cause breathing problems like wheezing and shortness of breath (asthma). Some allergens, such as foods, are a problem all year long. But others might bother people only during certain seasons. For instance, you might be allergic to pollen from trees, which is present in the air only in the spring.